Documents on a controversial government land deal were destroyed months after the sale came under scrutiny by the audit office, an Assembly committee has been told.

A military base in Belfast's Malone Road was found to have been sold for £1 million below its estimated value, only to be resold the same day by the new owner.

Members of Stormont's Public Accounts Committee grilled senior civil servants over the affair for more than two hours and demanded answers after learning documents on the sale were destroyed in 2010, while auditors began looking at the case in 2009.

Officials said the document destruction came because civil service staff were moving into new offices but MLAs demanded to know who sanctioned the action. The former army base, one of a number handed to the Stormont Executive by the British Government, was sold for £3.8 million in October 2003, despite having been valued at between £4.3 million and £4.6 million.

The barracks was situated in the leafy south Belfast suburbs and luxury apartments built on the site set a new high for property pricing at the time. Sinn Fein's Mitchell McLaughlin asked officials from the Office of First Minister and Deputy First Minister (OFMDFM) and Land and Property Services if they had their "eyes wiped".

However when committee chair Paul Maskey pursued the timing of the destruction of documents about the sale and the point at which the Audit Office began its damning investigation, he expressed serious concerns.

"If a report began from the Audit Office in 2009 and then there's files destroyed in 2010, it seems very strange," said Mr Maskey. "Does it not seem strange to yourself?"

David Ross of Land and Property Services answered: "I see the point you're making. It does seem strange," before going on to tell the committee he would secure precise dates for when files were destroyed.

The committee chair Mr Maskey added: "It just seems strange. This is a couple of times where departments have come up in front of us where the audit office takes the approach to go in to look at an inquiry, yet files are destroyed. It is simply not good enough because what it tells the people out there is that there is something wrong, whether there is or there is not. But it certainly smells as if something is wrong and I don't think it is acceptable."

Mr Ross said the documents were destroyed during an office move by Land and Property Services but committee members demanded answers on the regulations under which the destruction was sanctioned and on who was responsible for the decision.